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gabrittogabritto
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Consider index signatures as optional properties in contextual type discrimination (#54596)
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5 files changed

+194
-4
lines changed

5 files changed

+194
-4
lines changed

‎src/compiler/checker.ts‎

Lines changed: 7 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -10165,8 +10165,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
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return prop ? getTypeOfSymbol(prop) : undefined;
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}
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10168-
function getTypeOfPropertyOrIndexSignature(type: Type, name: __String): Type {
10169-
return getTypeOfPropertyOfType(type, name) || getApplicableIndexInfoForName(type, name)?.type || unknownType;
10168+
function getTypeOfPropertyOrIndexSignature(type: Type, name: __String, addOptionalityToIndex: boolean): Type {
10169+
let propType;
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return getTypeOfPropertyOfType(type, name) ||
10171+
(propType = getApplicableIndexInfoForName(type, name)?.type) && addOptionality(propType, /*isProperty*/ true, addOptionalityToIndex) ||
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unknownType;
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}
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1017210175
function isTypeAny(type: Type | undefined) {
@@ -22700,7 +22703,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
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let matched = false;
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for (let i = 0; i < types.length; i++) {
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if (include[i]) {
22703-
const targetType = getTypeOfPropertyOfType(types[i], propertyName);
22706+
const targetType = getTypeOfPropertyOrIndexSignature(types[i], propertyName, /*addOptionalityToIndex*/ true);
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if (targetType && related(getDiscriminatingType(), targetType)) {
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matched = true;
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}
@@ -27013,7 +27016,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
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propType = removeNullable && optionalChain ? getOptionalType(propType) : propType;
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const narrowedPropType = narrowType(propType);
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return filterType(type, t => {
27016-
const discriminantType = getTypeOfPropertyOrIndexSignature(t, propName);
27019+
const discriminantType = getTypeOfPropertyOrIndexSignature(t, propName, /*addOptionalityToIndex*/ false);
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return !(discriminantType.flags & TypeFlags.Never) && !(narrowedPropType.flags & TypeFlags.Never) && areTypesComparable(narrowedPropType, discriminantType);
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});
2701927022
}

‎tests/baselines/reference/discriminatedUnionWithIndexSignature.js‎

Lines changed: 44 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,44 @@
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//// [tests/cases/compiler/discriminatedUnionWithIndexSignature.ts] ////
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//// [discriminatedUnionWithIndexSignature.ts]
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export interface UnionAltA {
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type?: 'text';
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}
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export interface UnionAltB {
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type?: 'image' | 'video' | 'document';
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}
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export type ValueUnion = UnionAltA | UnionAltB;
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export type MapOrSingleton =
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| {
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[key: string]: ValueUnion;
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}
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| ValueUnion;
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const withoutAsConst: MapOrSingleton = {
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1: {
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type: 'text' /*as const*/,
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},
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};
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const withAsConst: MapOrSingleton = {
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1: {
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type: 'text' as const,
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},
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};
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//// [discriminatedUnionWithIndexSignature.js]
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"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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var withoutAsConst = {
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1: {
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type: 'text' /*as const*/,
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},
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};
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var withAsConst = {
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1: {
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type: 'text',
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},
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};

‎tests/baselines/reference/discriminatedUnionWithIndexSignature.symbols‎

Lines changed: 59 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,59 @@
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//// [tests/cases/compiler/discriminatedUnionWithIndexSignature.ts] ////
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=== discriminatedUnionWithIndexSignature.ts ===
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export interface UnionAltA {
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>UnionAltA : Symbol(UnionAltA, Decl(discriminatedUnionWithIndexSignature.ts, 0, 0))
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type?: 'text';
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>type : Symbol(UnionAltA.type, Decl(discriminatedUnionWithIndexSignature.ts, 0, 28))
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}
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export interface UnionAltB {
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>UnionAltB : Symbol(UnionAltB, Decl(discriminatedUnionWithIndexSignature.ts, 2, 1))
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type?: 'image' | 'video' | 'document';
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>type : Symbol(UnionAltB.type, Decl(discriminatedUnionWithIndexSignature.ts, 4, 28))
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}
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export type ValueUnion = UnionAltA | UnionAltB;
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>ValueUnion : Symbol(ValueUnion, Decl(discriminatedUnionWithIndexSignature.ts, 6, 1))
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>UnionAltA : Symbol(UnionAltA, Decl(discriminatedUnionWithIndexSignature.ts, 0, 0))
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>UnionAltB : Symbol(UnionAltB, Decl(discriminatedUnionWithIndexSignature.ts, 2, 1))
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export type MapOrSingleton =
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>MapOrSingleton : Symbol(MapOrSingleton, Decl(discriminatedUnionWithIndexSignature.ts, 8, 47))
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| {
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[key: string]: ValueUnion;
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>key : Symbol(key, Decl(discriminatedUnionWithIndexSignature.ts, 12, 9))
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>ValueUnion : Symbol(ValueUnion, Decl(discriminatedUnionWithIndexSignature.ts, 6, 1))
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}
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| ValueUnion;
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>ValueUnion : Symbol(ValueUnion, Decl(discriminatedUnionWithIndexSignature.ts, 6, 1))
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const withoutAsConst: MapOrSingleton = {
35+
>withoutAsConst : Symbol(withoutAsConst, Decl(discriminatedUnionWithIndexSignature.ts, 16, 5))
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>MapOrSingleton : Symbol(MapOrSingleton, Decl(discriminatedUnionWithIndexSignature.ts, 8, 47))
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1: {
39+
>1 : Symbol(1, Decl(discriminatedUnionWithIndexSignature.ts, 16, 40))
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type: 'text' /*as const*/,
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>type : Symbol(type, Decl(discriminatedUnionWithIndexSignature.ts, 17, 8))
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},
45+
};
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const withAsConst: MapOrSingleton = {
48+
>withAsConst : Symbol(withAsConst, Decl(discriminatedUnionWithIndexSignature.ts, 22, 5))
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>MapOrSingleton : Symbol(MapOrSingleton, Decl(discriminatedUnionWithIndexSignature.ts, 8, 47))
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1: {
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>1 : Symbol(1, Decl(discriminatedUnionWithIndexSignature.ts, 22, 37))
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type: 'text' as const,
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>type : Symbol(type, Decl(discriminatedUnionWithIndexSignature.ts, 23, 8))
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>const : Symbol(const)
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},
59+
};

‎tests/baselines/reference/discriminatedUnionWithIndexSignature.types‎

Lines changed: 55 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,55 @@
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//// [tests/cases/compiler/discriminatedUnionWithIndexSignature.ts] ////
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=== discriminatedUnionWithIndexSignature.ts ===
4+
export interface UnionAltA {
5+
type?: 'text';
6+
>type : "text" | undefined
7+
}
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9+
export interface UnionAltB {
10+
type?: 'image' | 'video' | 'document';
11+
>type : "image" | "video" | "document" | undefined
12+
}
13+
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export type ValueUnion = UnionAltA | UnionAltB;
15+
>ValueUnion : UnionAltA | UnionAltB
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export type MapOrSingleton =
18+
>MapOrSingleton : ValueUnion | { [key: string]: ValueUnion; }
19+
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| {
21+
[key: string]: ValueUnion;
22+
>key : string
23+
}
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| ValueUnion;
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const withoutAsConst: MapOrSingleton = {
27+
>withoutAsConst : MapOrSingleton
28+
>{ 1: { type: 'text' /*as const*/, },} : { 1: { type: "text"; }; }
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1: {
31+
>1 : { type: "text"; }
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>{ type: 'text' /*as const*/, } : { type: "text"; }
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type: 'text' /*as const*/,
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>type : "text"
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>'text' : "text"
37+
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},
39+
};
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const withAsConst: MapOrSingleton = {
42+
>withAsConst : MapOrSingleton
43+
>{ 1: { type: 'text' as const, },} : { 1: { type: "text"; }; }
44+
45+
1: {
46+
>1 : { type: "text"; }
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>{ type: 'text' as const, } : { type: "text"; }
48+
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type: 'text' as const,
50+
>type : "text"
51+
>'text' as const : "text"
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>'text' : "text"
53+
54+
},
55+
};

‎tests/cases/compiler/discriminatedUnionWithIndexSignature.ts‎

Lines changed: 29 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,29 @@
1+
// @strict: true
2+
3+
export interface UnionAltA {
4+
type?: 'text';
5+
}
6+
7+
export interface UnionAltB {
8+
type?: 'image' | 'video' | 'document';
9+
}
10+
11+
export type ValueUnion = UnionAltA | UnionAltB;
12+
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export type MapOrSingleton =
14+
| {
15+
[key: string]: ValueUnion;
16+
}
17+
| ValueUnion;
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const withoutAsConst: MapOrSingleton = {
20+
1: {
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type: 'text' /*as const*/,
22+
},
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};
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const withAsConst: MapOrSingleton = {
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1: {
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type: 'text' as const,
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},
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};

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